im the only warlock in my raid team right now and i’ve been dying to play affliction but in phase 4 they had Shadowflame, a major throughput rune for aff, conflict with Mark of Chaos, an important supportive party buff. They finally moved Shadowflame and Mark of Chaos to different rune slots but its STILL conflicting with another throughput rune, meaning affliction is still off the table for me in my single warlock raid group.
Mark of Chaos currently resides on the back slot which makes it conflict with Soul Drain which boosts the damage of drain life by 18%.